The present invention relates to a catalyst for use in the polymerization of alpha olefins. More particularly, the present invention relates to a catalyst system comprising a titanium-containing component and a second component comprising a mixture of a dialkyl aluminum halide and a dialkyl magnesium compound.
It is known in the art that extremely reactive Ziegler-type catalysts can be prepared by reacting titanium tetrachloride with ethanol in the presence of a pulverized solid support, such as magnesium chloride. Frequently, esters of aromatic carboxylic acids are included in this preparation. The resulting solid complex is then mixed with a trialkyl aluminum compound, such as tri-isobutyl aluminum, to produce the final catalyst. When used to polymerize alpha olefins, these catalysts provide high yields of stereoregular polymer per part of catalyst. As a result, the catalyst normally does not have to be separated from the polymer to give a final polymer product of specification purity.
Accordingly, U.S. Pat. No. 4,143,223 describes a catalyst composition comprising a mechanically pulverized solid halogen-containing titanium catalyst component and an organoaluminum compound. The titanium catalyst component is obtained by reacting a titanium compound, such as titanium tetrachloride, with a pulverized solid product derived from a magnesium compound, an organic acid ester and an active hydrogen-containing compound selected from alcohols and phenols.
U.S. Pat. No. 4,107,415 describes a catalyst system comprising a catalyst-forming component which is an addition and/or substitution product of an electron-donor compound (or Lewis base) and an alkyl aluminum compound, and a supported catalyst-forming component obtained by contacting a titanium compound with a carrier which is a mixture of an active magnesium or manganese dihalide and a solid organic material which is inert to all other catalyst components. The electron-donor compound is typically an organic acid ester and the inert solid organic material is a compound such as durene, anthracene, acenaphthene or diphenyl.
Chemical Abstracts, 96:69614c (1982) describes a polymerization catalyst comprising an organic aluminum compound, such as triethyl aluminum, and a solid component obtained by reacting milled mixtures of magnesium dichloride, aromatic carboxylic acid esters and silicon tetrachloride with titanium tetrahalide in the presence of chlorinated hydrocarbons, such as dichloroethane.